Sound-reproducing device



July 18, 1933. M. NYsTRoM SOUND REPRODUCING DEVICE Filed June 22, 1926 Patented July '18, 1933 UNITED STATES PATENT OFFICE MARTIN NYSTROM, `F CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO UNITED RESEARCH CORPORATION, 0F LONG ISLAND CITY, NEW YORK, A CORPORA- TION OF DELAWARE Application filed June 22,

My invention relates to devices for transmitting ,or reproducing sound and it has a special relation to sound-boxes for phonographs. A

One object of my invention is to produce a diaphragm for reproducing sound which 10, construction that it will endure constant and will be extremely sensitive so as to faithfully reproduce sounds over a Wide range of frequencies and at the same time Will be of such prolonged usage Without in any manner getting out of order or impairing the excellence of the reproduction.

Another object of the invention is to prof vide a 10W mass one-piece diaphragm having a portion of extreme thinness to reduce the Weight and facilitate flexure' thereof.

A further object of the invent1on 1s to provide a method of making diaphragms of the type described.

Other objects and advantages will appearas the description proceeds.

Referring to the accompanying drawing, Figure 1 is a central sectional vleW. of a sound-box embodying theinvention; Figures 2 and 3 are central sectional views illustrating a diaphragm embodied in the sound-box illustrated in Figure l, the views being taken at dilierent steps in the formation of the diaphragm; Figure 4 is a central sectional view of a completed diaphragm; Flgure 5 1s an elevational view of the outer side of the completed diaphragm and Figure 6 is a central sectional view illustrating a modified form of diaphragm. D

The diaphragm is extremely thin and comprises a central rigid portion or piston and an outer flexible portion or hinge l of reduced thickness. The hinge may be secured in a sound box 2 by means of Washers 3.

In order that the piston may exercise a true piston action and not be flexed in operation, it may be deformed. The deformation may be in the shape of a cone 4, which may be slightly flattened at the apex for securement to a stylus bar 5.

Radial deformations 6 may also he provided in the cone 4 to further insure rigidity. 'An annular deformation 7 having Vmeeting 192e. serial-N0. 117,723.

truncoconical faces and surrounding the cone 4l may also be provided for increasing the rigid area of the central portion or piston.

To facilitate iexure of the hinge 1 it may have deformations therein. These may be in the shape of annular corrugations 8.

rlhe diaphragm may be made'of a'desired material, a light metal such as aluminum or aluminum alloy being especially advantageous, and latitude in the thickness and dimensions of the'diaphragm is contemplated. A n embodiment of the invention in which the diaphragm was made of aluminum and was approximately .004 in thickness throughout the piston area and approximately .002 in the hinge was found to be very satisfactory.

ln the embodiment of the invention illustrated in Figures l to 5 inclusive, the reduction in thickness of the diaphragm occurs along aline l0 at the outer border of deformation 7.

ln the modiied embodiment of the invention illustrated in Figure 6, the reduction in thickness of the diaphragm occurs at the base of the cone 4. rllhis increases the iexible area.

The low mass of diaphragms embodying the invention and the readily flexible character of the exterior portion or hinge makes possible a faithful reproduction of sound over a wide range oi frequencies. The character of the diaphragm as `being in one piece and lacking in joints, renders it very durable. Diaphragms made in accordance with the invention have no tendency to deteriorate even after long usage. There is no tendency ot the piston to tear loose from the hinge or of the stylus bar to tear loose from the piston.

In making the diaphragm a central blank of a desired material, such, for instance, as

.i aluminum or an aluminum alloy may be used,

the blank being oi a desired thickness as, for instance9 .004". An outer marginal portion of the blank may be reduced to a desired thickness, as for instance, l.002.

The reduction in thickness may be produced by grinding either or both faces of the outer portion of the blank or by subjecting the outer portion of the blank to compression between dies in such a manner as described in my copending application Serial No. 120,161 filed July 2, 1926, now Patent No. 1,7 83,386, Dec. 2, 1930. Figure 2, illustrates the condition of Athe blank at this stage of its manufacture.

The central portion may then be shaped into a cone 4f, and a deformation 7 by the action of suitable dies as illustrated in Figure 3.

The radial deformations 6 and the corrugations 8 may then be impressed by suitable dies, the diaphragm taking the shape illustrated in Figure 4, but the invention is not limited to a precise sequence of steps in the formation of deformations and corrugations, as these may be formed simultaneously or in any desired order.

The invention is not limited to the specific details of construction of the embodiments illustrated and described, but is capable of diversified embodiment and the diaphragm may be used not only inlsound-boxes, but in loud-speakers, telephones and other devices in which it is desired to transmit or reproduce sound. A substantial range of equivalents is contemplated within scope of the appended claims.

I claim:

1. A diaphragm composed of aluminum and having a central portion, deformed to prevent exure thereof, in one piece with a relatively thin outer portion, deformed to facilitate flexure thereof.

2. A metal diaphragm having a central portion, deformed into the shape of a cone to prevent fiexure thereof, and a relatively thinner outer portion formed in one piece With the central portion and having therein annular corrugations to facilitate lexure thereof.

3. A diaphragm composed of a light metal and having an Outer portion relatively thinner than and in one piece with a central portion, said central portion being deformed into the shape of a cone, and said cone being surrounded by an annular deformation having meeting truncoconical faces.

4. A diaphragm composed of an extremely light metal having a central portion reinforced by radial deformations and in one piece with an outer relatively thinner flexible portion.

5. A diaphragm comprising a thin central portion, deformed substantially into the shape of a cone, in one piece with a thinner outer portion, the reduction in thickness occurring substantially at the base of said cone.

6. A diaphragm composed of an extremely light metal and comprising a rigid central portion having the shape of a cone, 'and being approximately .004 in thickness uniformly throughout, and a flexible outer portion in one piece with said central portion and having deformations therein to facilitate flexure thereof, said flexible outer portion being approximately .002 in thickness throughout.

MARTIN NYSTROM.

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